JP2012006907A - Salt for acid-generating agent and resist composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a salt for an acid-generating agent of a resist composition which can form patterns having excellent resolution and line edge roughness.SOLUTION: There is provided the salt represented by formula (I) and comprising a triaryl sulfonium cation and α, α-difluoroadamantyloxycarbonyl methane sulfonate anion. A photoresist composition is especially useful for chemical amplification type photoresist compositions, and can suitably be used for wide uses such as fine processing of semiconductors, liquid crystals, the production of circuit boards for thermal heads and the like, and other photofabrication processes. The photoresist composition can especially be used as a chemical amplification type photoresist composition suitable for ArF or KrF excimer laser lithography, ArF immersion exposure lithography, EB exposure lithography, and EUV exposure lithography. The photoresist composition can also be used for immersion exposure, dry exposure and the like.

Description

  The present invention relates to a salt for an acid generator and a resist composition.

A resist composition used for fine processing of a semiconductor using a lithography technique contains an acid generator.
Patent Document 1 describes a salt represented by the following as an acid generator.

JP 2007-161707 A

  Conventional salt for an acid generator may not always satisfy the resolution and line edge roughness of a pattern obtained from a resist composition containing the salt.

［式（Ｉ）中、
Ｑ^１及びＱ^２は、互いに独立に、フッ素原子又はＣ_1-6ペルフルオロアルキル基を表す。
Ｌ^１は、Ｃ_1-17アルキレン基を表し、前記アルキレン基に含まれる−ＣＨ_２−は、−Ｏ−又は−ＣＯ−で置き換わっていてもよい。
Ｒ^１は、Ｃ_1-１２炭化水素基を表す。
環Ｗ^１は、Ｃ_３-３６飽和炭化水素環を表す。
Ｒ^２は、Ｃ_1-６アルキル基又はＣ_1-6アルコキシ基を表す。
ｓは、０〜２の整数を表す。ｓが２である場合、２つのＲ^２は同じであっても異なっていてもよい。
Ｒ^３は、式（Ｒ^３−１）で表される基、式（Ｒ^３−２）で表される基又は式（Ｒ^３−３）で表される基を表す。

［式（Ｒ^３−１）中、Ａ^１は、Ｃ_1-6アルキレン基を表す。
Ｒ^４は、Ｃ_1-６アルキル基を表す。］

［式（Ｒ^３−２）中、Ｒ^５、Ｒ^６及びＲ^７は、それぞれ独立に、Ｃ_1-６アルキル基を表す。］

［式（Ｒ^３−３）中、Ｒ^５’、Ｒ^６’及びＲ^７’は、それぞれ独立に、Ｃ_1-６アルキル基を表す。］
ｔは、１〜３の整数を表す。ｔが２又は３である場合、複数のＲ^３は同じであっても異なっていてもよい。
Ｚ^＋は、有機対イオンを表す。］ The present invention includes the following inventions.
[1] A salt represented by the formula (I).

[In the formula (I),
Q ¹ and Q ² each independently represent a fluorine atom or a C _1-6 perfluoroalkyl group.
L ¹ represents a C _1-17 alkylene group, and —CH ₂ — contained in the alkylene group may be replaced by —O— or —CO—.
R ¹ represents a C _1-12 hydrocarbon group.
Ring W ¹ represents a C _3-36 saturated hydrocarbon ring.
R ² represents a C _1-6 alkyl group or a C _1-6 alkoxy group.
s represents the integer of 0-2. When s is 2, two R ² may be the same or different.
R ³ represents a group represented by the formula (R ³ -1), a group represented by the formula (R ³ -2) or a group represented by the formula (R ³ -3).

[In Formula (R ³ -1), A ¹ represents a C _1-6 alkylene group.
R ⁴ represents a C _1-6 alkyl group. ]

[In formula (R ³ -2), R ⁵ , R ⁶ and R ⁷ each independently represents a C _1-6 alkyl group. ]

[In the formula (R ³ -3), R ^{5 ′} , R ^{6 ′} and R ^{7 ′} each independently represents a C _1-6 alkyl group. ]
t represents an integer of 1 to 3. When t is 2 or 3, the plurality of R ³ may be the same or different.
Z ⁺ represents an organic counter ion. ]

[2] L ¹ is * —CO—O— or * —CO—O—CH ₂ —CO—O— (* represents a bond to —C (Q ¹ ) (Q ² ) —). The salt according to [1].

[3] The salt according to [1] or [2], wherein Z ⁺ is a triarylsulfonium cation.

[4] An acid generator containing the salt according to any one of [1] to [3].

[5] The acid generator according to [4] and a resin are contained, the resin has an acid labile group and is insoluble or hardly soluble in an alkaline aqueous solution, and is dissolved in an alkaline aqueous solution by the action of an acid. Resist composition which is resin which can be done.

[6] The resist composition according to [5], further containing a basic compound.

[7] (1) A step of applying the resist composition according to [5] or [6] on a substrate,
(2) The process of drying the composition after application | coating and forming a composition layer,
(3) a step of exposing the composition layer using an exposure machine;
(4) A step of heating the composition layer after exposure,
(5) a step of developing the heated composition layer using a developing device;
A method for producing a resist pattern including:

  According to the salt of the present invention, a pattern having excellent resolution and line edge roughness can be obtained from a resist composition containing the salt.

［式（Ｉ）中、
Ｑ^１及びＱ^２は、互いに独立に、フッ素原子又はＣ_1-6ペルフルオロアルキル基を表す。
Ｌ^１は、Ｃ_1-17アルキレン基を表し、前記アルキレン基に含まれる−ＣＨ_２−は、−Ｏ−又は−ＣＯ−で置き換わっていてもよい。
Ｒ^１は、Ｃ_1-１２炭化水素基を表す。
環Ｗ^１は、Ｃ_３-３６飽和炭化水素環を表す。
Ｒ^２は、Ｃ_1-６アルキル基又はＣ_1-6アルコキシ基を表す。
ｓは、０〜２の整数を表す。ｓが２である場合、２つのＲ^２は同じであっても異なっていてもよい。
Ｒ^３は、式（Ｒ^３−１）で表される基、式（Ｒ^３−２）で表される基又は式（Ｒ^３−３）で表される基を表す。

［式（Ｒ^３−１）中、Ａ^１は、Ｃ_1-6アルキレン基を表す。
Ｒ^４は、Ｃ_1-６アルキル基を表す。］

［式（Ｒ^３−２）中、Ｒ^５、Ｒ^６及びＲ^７は、それぞれ独立に、Ｃ_1-６アルキル基を表す。］

［式（Ｒ^３−３）中、Ｒ^５’、Ｒ^６’及びＲ^７’は、それぞれ独立に、Ｃ_1-６アルキル基を表す。］
ｔは、１〜３の整数を表す。ｔが２又は３である場合、複数のＲ^３は同じであっても異なっていてもよい。
Ｚ^＋は、有機対イオンを表す。］ <Salt represented by formula (I)>
The salt of the present invention is represented by the formula (I).

[In the formula (I),
Q ¹ and Q ² each independently represent a fluorine atom or a C _1-6 perfluoroalkyl group.
L ¹ represents a C _1-17 alkylene group, and —CH ₂ — contained in the alkylene group may be replaced by —O— or —CO—.
R ¹ represents a C _1-12 hydrocarbon group.
Ring W ¹ represents a C _3-36 saturated hydrocarbon ring.
R ² represents a C _1-6 alkyl group or a C _1-6 alkoxy group.
s represents the integer of 0-2. When s is 2, two R ² may be the same or different.
R ³ represents a group represented by the formula (R ³ -1), a group represented by the formula (R ³ -2) or a group represented by the formula (R ³ -3).

[In Formula (R ³ -1), A ¹ represents a C _1-6 alkylene group.
R ⁴ represents a C _1-6 alkyl group. ]

[In formula (R ³ -2), R ⁵ , R ⁶ and R ⁷ each independently represents a C _1-6 alkyl group. ]

[In the formula (R ³ -3), R ^{5 ′} , R ^{6 ′} and R ^{7 ′} each independently represents a C _1-6 alkyl group. ]
t represents an integer of 1 to 3. When t is 2 or 3, the plurality of R ³ may be the same or different.
Z ⁺ represents an organic counter ion. ]

In the present specification, “C _ab ” means “the number of carbon atoms is ab”.
Q ¹ and Q ² each independently represents a fluorine atom or a C _1-6 perfluoroalkyl group. Examples of the perfluoroalkyl group include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butyl group, a perfluorotert-butyl group, a perfluoropentyl group, and a perfluorohexyl group. . Q ¹ and Q ² are each independently preferably a perfluoromethyl group or a fluorine atom, more preferably a fluorine atom.

L ¹ represents a C _1-17 alkylene group. Examples of the alkylene group include a linear alkylene group and a branched alkylene group.
Examples of the linear alkylene group include a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, and a hexane-1,6-diyl group. , Heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1, 12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group Can be mentioned.
Examples of the branched alkylene group include, for example, a C _1-4 alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group) to the linear alkylene group. And the like, to which a side chain is added.
L ¹ may be a combination of two or more of these groups.

L ¹ —CH ₂ — may be replaced by —O— or —CO—. L ¹ is preferably any one of formulas (b1-1) to (b1-6), more preferably any of formulas (b1-1) to (b1-4), and even more preferably formula (b1- 1) or represented by formula (b1-2). Note the formula (b1-1) ~ formula (b1-6) is a left side ^{C (Q 1) (Q 2} ) - bound to, binds to the ring ^{W 1} on the right. The same applies to specific examples of the following formulas (b1-1) to (b1-6).

Formula (b1-1) and L ^b2 represent a single bond or a C _1-15 alkylene group.
In formula (b1-2), L ^b3 represents a single bond or a C _1-12 alkylene group, and L ^b4 represents a C _1-13 alkylene group. However, the upper limit of the carbon number of L ^b3 and L ^b4 is 13 or less.
In formula (b1-3), L ^b5 represents a C _1-15 alkylene group.
In formula (b1-4), L ^b6 and L ^b7 each independently represent a C _1-15 alkylene group. However, the upper limit of the carbon number of L ^b6 and L ^b7 is 16 or less.
In formula (b1-5), L ^b8 represents a C _1-14 alkylene group.
In formula (b1-6), L ^b9 and L ^b10 each independently represent a C _1-11 alkylene group. However, the upper limit of the carbon number of L ^b6 and L ^b7 is 12 or less.
Among these, a divalent group represented by the formula (b1-1) is preferable, and a divalent group represented by the formula (b1-1) in which L ^b2 is a single bond or —CH ₂ — is more preferable.

  Examples of the divalent group represented by the formula (b1-1) include the following.

  Examples of the divalent group represented by the formula (b1-2) include the following.

  Examples of the divalent group represented by the formula (b1-3) include the following.

  Examples of the divalent group represented by the formula (b1-4) include the following.

  Examples of the divalent group represented by the formula (b1-5) include the following.

  Examples of the divalent group represented by the formula (b1-6) include the following.

R ¹ represents a C _1-12 hydrocarbon group.

Examples of the C _1-12 hydrocarbon group include a C _1-12 alkyl group, a C _3-12 saturated cyclic hydrocarbon group, and a group obtained by combining these.

Specific examples of the C _1-12 alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, 1- Methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylpropyl group, 2-ethylpropyl group, n-hexyl group, 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 4- Methylpentyl group, 1-ethylbutyl group, 2-ethylbutyl group, 3-ethylbutyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, isopropyl Group, sec-butyl group, tert-butyl group, 2-ethylhexyl group, alkyl group such as tert-octyl group, and the like.

などが挙げられる。 The C _3-12 saturated cyclic hydrocarbon group includes a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a 1-adamantyl group, a 2-adamantyl group, an isobornyl group,

Etc.

Specific examples of the group represented by the formula (IA) include the following groups.

Examples of the substituent R ² that the ring W ¹ may have include a C _1-6 alkyl group and a C _1-6 alkoxy group.
Examples of the C _1-6 alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group. A C _1-4 alkyl group is preferred, a C _1-2 alkyl group is more preferred, and a methyl group is particularly preferred.
Examples of the C _1-6 alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentoxy group, and an n-hexoxy group. A C _1-4 alkoxy group is preferable, a C _1-2 alkoxy group is more preferable, and a methoxy group is particularly preferable.

［式（Ｒ^３−１）中、Ａ^１は、Ｃ_1-6アルキレン基を表す。
Ｒ^４は、Ｃ_1-６アルキル基を表す。］ R ³ represents a group represented by the formula (R ³ -1), a group represented by the formula (R ³ -2) or a group represented by the formula (R ³ -3).

[In Formula (R ³ -1), A ¹ represents a C _1-6 alkylene group.
R ⁴ represents a C _1-6 alkyl group. ]

［式（Ｒ^３−２）中、Ｒ^５、Ｒ^６及びＲ^７は、それぞれ独立に、Ｃ_1-６アルキル基を表す。］

[In formula (R ³ -2), R ⁵ , R ⁶ and R ⁷ each independently represents a C _1-6 alkyl group. ]

［式（Ｒ^３−３）中、Ｒ^５’、Ｒ^６’及びＲ^７’は、それぞれ独立に、Ｃ_1-６アルキル基を表す。］

[In the formula (R ³ -3), R ^{5 ′} , R ^{6 ′} and R ^{7 ′} each independently represents a C _1-6 alkyl group. ]

t represents an integer of 1 to 3. When t is 2 or 3, the plurality of R ³ may be the same or different.

_{Examples of the} C _1-6 alkylene group include a linear alkylene group and a branched alkylene group.
Examples of the linear alkylene group include a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, and a hexane-1,6-diyl group. Is mentioned.
Examples of the branched alkylene group include, for example, a C _1-4 alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group) to the linear alkylene group. And the like, to which a side chain is added.

Specific examples of the group represented by the formula (R ³ -1) include the following groups.

Specific examples of the group represented by the formula (R ³ -2) include the following groups.

Specific examples of the group represented by the formula (R ³ -3) include the following groups.

  t is preferably 0 or 1, and more preferably 0.

Examples of the salt represented by the formula (I) include the following salts.

Examples of Z ⁺ include onium cations such as sulfonium cations, iodonium cations, ammonium cations, benzothiazolium cations, and phosphonium cations. Among these, a sulfonium cation and an iodonium cation are preferable, and an arylsulfonium cation is more preferable.

Z ⁺ is preferably represented by any one of formulas (b2-1) to (b2-4).

In formula (b2-1), R ^{b4 to} R ^b6 each independently represent a C _1-30 aliphatic hydrocarbon group, a C _3-36 saturated cyclic hydrocarbon group or a C _6-18 aromatic hydrocarbon group. . The aliphatic hydrocarbon group may be substituted with a hydroxy group, a C _1-12 alkoxy group or a C _6-18 aromatic hydrocarbon group, and the saturated cyclic hydrocarbon group is a halogen atom, C _2-4 The aromatic hydrocarbon group which may be substituted with an acyl group or a glycidyloxy group is a halogen atom, a hydroxy group, a C _1-36 aliphatic hydrocarbon group, a C _3-36 saturated cyclic hydrocarbon group or C _It may be substituted with a _1-12 alkoxy group.

In formula (b2-2), R ^b7 and R ^b8 each independently represent a hydroxy group, a C _1-12 aliphatic hydrocarbon group or a C _1-12 alkoxy group, and m2 and n2 each independently represent 0 Represents an integer of ~ 5.

In formula (b2-3), R ^b9 and R ^b10 each independently represent a C _1-36 aliphatic hydrocarbon group or a C _3-36 saturated cyclic hydrocarbon group. R ^b11 represents a hydrogen atom, a C _1-36 aliphatic hydrocarbon group, a C _3-36 saturated cyclic hydrocarbon group or a C _6-18 aromatic hydrocarbon group. The carbon number of the aliphatic hydrocarbon group of R ^{b9 to} R ^b11 is preferably 1 to 12, and the carbon number of the saturated cyclic hydrocarbon group is preferably 3 to 36, more preferably 4 to 12. R ^b12 represents a C _1-12 aliphatic hydrocarbon group, a C _3-18 saturated cyclic hydrocarbon group, or a C _6-18 aromatic hydrocarbon group. The aromatic hydrocarbon group may be substituted with a C _1-12 aliphatic hydrocarbon group, a C _1-12 alkoxy group, a C _3-18 saturated cyclic hydrocarbon group or an alkylcarbonyloxy group. R ^b9 and R ^b10 , and R ^b11 and R ^b12 may be independently bonded to each other to form a 3- to 12-membered ring (preferably a 3- to 7-membered ring), In these rings, —CH ₂ — may be replaced by —O—, —S—, or —CO—.

In formula (b2-4), R ^{b13 to} R ^b18 each independently represent a hydroxy group, a C _1-12 aliphatic hydrocarbon group, or a C _1-12 alkoxy group. L ^b11 represents -S- or -O-. o2, p2, s2, and t2 each independently represent an integer of 0 to 5, q2 and r2 each independently represent an integer of 0 to 4, and u2 represents 0 or 1. When any of o2 to t2 is 2, any of the plurality of R ^{b13 to} R ^b18 may be the same as or different from each other.

Next, substituents included in the formulas (b2-1) to (b2-4) will be described. Examples of the aliphatic hydrocarbon group, saturated cyclic hydrocarbon group and aromatic hydrocarbon group include those described above. Preferred aliphatic hydrocarbon groups are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, and 2-ethylhexyl. It is a group. Preferred saturated cyclic hydrocarbon groups are cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclodecyl group, 2-alkyl-2-adamantyl group, 1- (1-adamantyl) -1-alkyl group, And an isobornyl group. Preferred aromatic hydrocarbon groups are phenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, 4-cyclohexylphenyl group, 4-methoxyphenyl group, biphenylyl group, naphthyl group. It is. Examples of the aliphatic hydrocarbon group (aralkyl group) whose substituent is an aromatic hydrocarbon group include a benzyl group. Examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy, n-hexoxy, heptoxy, octoxy Group, 2-ethylhexyloxy group, nonyloxy group, decyloxy group, undecyloxy group, dodecyloxy group and the like. Examples of the ring formed by R ^b9 and R ^b10 include a thiolane-1-ium ring (tetrahydrothiophenium ring), a thian-1-ium ring, and a 1,4-oxathian-4-ium ring. ^Examples of the ring formed by R ^b11 and R ^b12 include an oxocycloheptane ring, an oxocyclohexane ring, an oxonorbornane ring, and an oxoadamantane ring.

  Among the cations (b2-1) to (b2-4), the cation (b2-1) is preferable, the cation represented by the formula (b2-1-1) is more preferable, and the triphenylsulfonium cation (formula (b2) In (1-1), v2 = w2 = x2 = 0) is more preferable.

In formula (b2-1-1), R ^{b19 to} R ^b21 each independently represent a halogen atom, a hydroxy group, a C _1-36 aliphatic hydrocarbon group, a C _3-36 saturated cyclic hydrocarbon group or C _{1- 12} represents an alkoxy group. The aliphatic hydrocarbon group preferably has 1 to 12 carbon atoms, and the saturated cyclic hydrocarbon group preferably has 4 to 36 carbon atoms. The aliphatic hydrocarbon group may be substituted with a hydroxy group, a C _1-12 alkoxy group or a C _6-18 aromatic hydrocarbon group, and the saturated cyclic hydrocarbon group may be a halogen atom, C _2-4 It may be substituted with an acyl group or a glycidyloxy group. v2 to x2 each independently represents an integer of 0 to 5 (preferably 0 or 1). When any one of v2 to x2 is 2 or more, any one of the plurality of R ^{b19 to} R ^b21 may be the same as or different from each other.

R ^{b19 to} R ^b21 in formula (b2-1-1) are preferably each independently a halogen atom (more preferably a fluorine atom), a hydroxy group, a C _1-12 alkyl group, or a C _1-12 alkoxy. And v2 to x2 each independently represents an integer of 0 to 5 (preferably 0 or 1).

  Specific examples of the cation (b2-1-1) include the following.

  Specific examples of the cation (b2-2) include the following.

  Specific examples of the cation (b2-3) include the following.

  Specific examples of the cation (b2-4) include the following.

  The salt represented by the formula (I) is a combination of the above-mentioned anions and organic cations. Although the above-mentioned anion and cation can be combined arbitrarily, the salt represented below is preferable.

[ ^Wherein , R ^{b19 to} R ^b21 and v2 to x2 represent the same meaning as described above. ]

Of these, the following salts are preferred.

The salt represented by the formula (I) can be produced by the following method.
For example, a method for producing a salt represented by the formula (I-1) wherein L ¹ is * —CO—O— (* represents a bond to —C (Q ¹ ) (Q ² ) —). It is shown below.

The compound represented by the formula (I-1-b) can be synthesized by the method described in JP-A-2008-13551.
The compound represented by the formula (I-1) by reacting the compound represented by the formula (I-1-a) with the compound represented by the formula (I-1-b) under a base catalyst. Can be obtained. Examples of the solvent include chloroform. Examples of the base catalyst include lithium amide.

For example, the manufacturing method of the salt represented by Formula (I-2) is shown below.

［Ｘ^１及びＸ^２は、それぞれ独立に、ハロゲン原子を表す。ハロゲン原子としては、フッ素原子、塩素原子、臭素原子及びヨウ素原子が挙げられ、塩素原子が好ましい。］ By reacting the compound represented by the formula (I-1-a) and the compound represented by the formula (I-2-c) under a basic catalyst, the compound represented by the formula (I-2-d) is obtained. Can be obtained. Examples of the solvent include tetrahydrofuran. Examples of the base catalyst include pyridine.
The salt represented by the formula (I-2) is reacted with the salt represented by the formula (I-1-b) and the compound represented by the formula (I-2-d) under a base catalyst. Obtainable. Examples of the solvent include chloroform. Examples of the base catalyst include lithium amide.

[X ¹ and X ² each independently represents a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a chlorine atom is preferable. ]

  The acid generator of the present invention contains a salt represented by the formula (I). When used as an acid generator, the salt represented by the formula (I) may be used alone or in combination of two or more.

The resist composition of the present invention contains an acid generator containing a salt represented by the formula (I) and a resin. The resin here is a resin that has an acid labile group, is insoluble or hardly soluble in an aqueous alkali solution, and can be dissolved in an aqueous alkali solution by the action of an acid. In the resist composition of the present invention, an acid is generated from the salt represented by the formula (I) by exposure. The acid catalyzes and cleaves the acid labile group in the resin, making the resin soluble in an aqueous alkaline solution. Such a resist composition of the present invention is suitable as a chemically amplified positive resist composition. However, in the resist composition of the present invention, as an acid generator, a known salt other than the salt represented by the formula (I), a cation contained in the salt represented by the formula (I), and a salt comprising a known anion In addition, an anion contained in the salt represented by the formula (I) and a salt composed of a known cation may be used in combination.
In the resist composition of the present invention, the content of the acid generator is preferably in the range of about 0.1 to 40% by weight in the solid content.

<Resin (hereinafter sometimes referred to as “resin (A)”)>
Resin (A) is a resin that becomes alkali-soluble by the action of an acid. A resin that becomes alkali-soluble by the action of an acid can be produced by polymerizing a monomer having an acid-labile group (hereinafter sometimes referred to as “monomer having an acid-labile group (a1)”), It becomes alkali-soluble by the action of acid. The phrase “becomes soluble in an alkali by the action of an acid” means “being insoluble or hardly soluble in an alkaline aqueous solution before contact with an acid, but soluble in an alkaline aqueous solution after contact with an acid”. . As the monomer (a1) having an acid labile group, one type may be used alone, or two or more types may be used in combination.

<Monomer (a1) having an acid labile group>
The “acid-labile group” means a group that cleaves a leaving group upon contact with an acid to form a hydrophilic group (for example, a hydroxy group or a carboxy group). Examples of the acid labile group include an alkoxycarbonyl group represented by the formula (1) in which —O— is bonded to a tertiary carbon atom (excluding a bridgehead carbon atom of a bridged cyclic hydrocarbon group) (ie, Ester bond having a tertiary alcohol residue). Hereinafter, the group represented by the formula (1) may be referred to as “acid-labile group (1)”.

In formula (1), R ^{a1 to} R ^a3 each independently represents an aliphatic hydrocarbon group or a saturated cyclic hydrocarbon group, or R ^a1 and R ^a2 may be bonded to each other to form a ring. Good. * Represents a bond.

Examples of the acid labile group (1) include a 1,1-dialkylalkoxycarbonyl group (in the group (1), R ^{a1 to} R ^a3 are alkyl groups, preferably a tert-butoxycarbonyl group), 2 -Alkyl-2-adamantyloxycarbonyl group (in formula (1), wherein R ^a1 , R ^a2 and a carbon atom form an adamantyl group, and R ^a3 is an alkyl group), and 1- (1-adamantyl)- 1-alkylalkoxycarbonyl groups (in the formula (1), R ^a1 and R ^a2 are alkyl groups and R ^a3 is an adamantyl group) and the like.

The monomer (a1) having an acid labile group is preferably a monomer having an acid labile group (1) and a carbon-carbon double bond, more preferably an acid labile group (1). (Meth) acrylic monomer having In the present specification, "(meth) acrylic monomer" means "CH ₂ = CH-CO-" or _{"CH 2 = C (CH 3)} -CO- " at least one monomer having the structure To do. Similarly, “(meth) acrylate” and “(meth) acrylic acid” mean “at least one of acrylate and methacrylate” and “at least one of acrylic acid and methacrylic acid”, respectively.

Among the (meth) acrylic monomers having the acid labile group (1), those having a C _5-20 saturated cyclic hydrocarbon group are preferred. If a resin obtained by polymerizing the monomer (a1) having a bulky structure such as a saturated cyclic hydrocarbon group is used, the resolution of the resist can be improved. The saturated cyclic hydrocarbon group may be monocyclic or polycyclic. Examples of the monocyclic saturated cyclic hydrocarbon group include a cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group) and a cycloalkenyl group (for example, cyclopentenyl group, cyclohexenyl group, cycloheptenyl group, Cyclooctenyl group) and the like. Examples of the polycyclic saturated cyclic hydrocarbon group include a group obtained by hydrogenating a condensed aromatic hydrocarbon group (for example, a hydronaphthyl group), a bridged cyclic hydrocarbon group (for example, an adamantyl group, a norbornyl group), and the like. . In addition, a group having a shape in which a bridged ring (for example, norbornane ring) and a single ring (for example, cycloheptane ring or cyclohexane ring) or a polycycle (for example, decahydronaphthalene ring) are condensed, or A group having a condensed shape is also included in the saturated cyclic hydrocarbon group.

  Among the (meth) acrylic monomers having the acid labile group (1) and the saturated cyclic hydrocarbon group, the acid labile group represented by the formula (a1-1) or the formula (a1-2) Monomers having are preferred. These may be used alone or in combination of two or more.

Formula (a1-1) and the formula (a1-2), L ^a1 and L ^a2 each independently, -O- or _{-O- (CH 2) k1 -CO-} O- the stands, k1 is 1 An integer of 7 is represented. However, —O— and the like enumerated for L ^a1 and L ^a2 are respectively bonded to —CO— of the formula (a1-1) and the formula (a1-2) on the left side, and to an adamantyl group or cyclohexyl group on the right side. Means to join. R ^a4 and R ^a5 each independently represent a hydrogen atom or a methyl group. R ^a6 and R ^a7 each independently represent a C _1-8 aliphatic hydrocarbon group or a C _3-10 saturated cyclic hydrocarbon group, m1 represents an integer of 0-14, and n1 represents 0-10. Represents an integer. The chemical formula in this specification includes stereoisomers.

L ^a1 and L ^a2 are preferably —O— or —O— (CH ₂ ) _f1 —CO—O— (wherein f1 is an integer of 1 to 4), more preferably —O—. is there.

R ^a4 and R ^a5 are preferably methyl groups. The carbon number of the aliphatic hydrocarbon group of R ^a6 and R ^a7 is preferably 6 or less, and the carbon number of the saturated cyclic hydrocarbon group is preferably 8 or less, more preferably 6 or less. Examples of the aliphatic hydrocarbon group represented by R ^a6 and R ^a7 include a methyl group, an ethyl group, a 1-methylethyl group (isopropyl group), a 1,1-dimethylethyl group (tert-butyl group), and 2,2-dimethyl. Ethyl group, propyl group, 1-methylpropyl group, 2,2-dimethylpropyl group, 1-ethylpropyl group, butyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-propylbutyl group, Examples include pentyl group, 1-methylpentyl group, hexyl group, 1,4-dimethylhexyl group, heptyl group, 1-methylheptyl group, octyl group and the like. Examples of the saturated cyclic hydrocarbon group for R ^a6 and R ^a7 include a cycloheptyl group, a methylcycloheptyl group, a cyclohexyl group, a methylcyclohexyl group, a dimethylcyclohexyl group, a norbornyl group, and a methylnorbornyl group.

  m1 is preferably an integer of 0 to 3, more preferably 0 or 1. n1 is 0, preferably an integer of 0 to 3, more preferably 0 or 1. k1 is preferably an integer of 1 to 4, more preferably 1.

  Examples of the monomer (a1-1) having an adamantyl group include the following, among which 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, and 2-Isopropyl-2-adamantyl (meth) acrylate is preferred, and one in the form of methacrylate is more preferred.

  Examples of the monomer (a1-2) having a cyclohexyl group include the following, among which 1-ethyl-1-cyclohexyl (meth) acrylate is preferable, and 1-ethyl-1-cyclohexyl methacrylate is more preferable. preferable.

  The content of the structural unit derived from the monomer represented by the formula (a1-1) or the formula (a1-2) in the resin is usually 10 to 95 mol%, preferably 15 to 90, in all units of the resin. It is mol%, More preferably, it is 20-85 mol%.

  Examples of the monomer having an acid labile group (1) and a carbon-carbon double bond include a monomer having a norbornene ring represented by the formula (a1-3). Since the resin having a structural unit derived from the monomer (a1-3) having an acid labile group has a bulky structure, the resolution of the resist can be improved. Furthermore, the monomer (a1-3) having an acid labile group can improve the resistance to dry etching of a resist by introducing a rigid norbornane ring into the main chain of the resin.

In formula (a1-3), R ^a9 represents a hydrogen atom, a C _1-3 aliphatic hydrocarbon group, a carboxy group, a cyano group, or an alkoxycarbonyl group (which may have a substituent (for example, a hydroxy group)). -COOR ^a13 ), R ^a13 represents a C _1-8 aliphatic hydrocarbon group or a C _3-8 saturated cyclic hydrocarbon group, and the hydrogen atoms of the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group are It may be substituted with a hydroxy group, and —CH ₂ — in the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group may be replaced with —O— or —CO—. R ^{a10 to} R ^a12 each independently represent a C _1-12 aliphatic hydrocarbon group or a C _3-12 saturated cyclic hydrocarbon group, or R ^a10 and R ^a11 are bonded to each other to form a ring. The hydrogen atom of the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group may be substituted with a hydroxy group or the like, and —CH ₂ — of the aliphatic hydrocarbon group and the saturated cyclic hydrocarbon group may be substituted. May be replaced by —O— or —CO—.

Examples of the aliphatic hydrocarbon group which may have a substituent for R ^a9 include a methyl group, an ethyl group, a propyl group, a hydroxymethyl group, and a 2-hydroxyethyl group. ^Examples of R ^a13 include a methyl group, an ethyl group, a propyl group, a 2-oxo-oxolan-3-yl group, and a 2-oxo-oxolan-4-yl group.

Examples of R ^{a10 to} R ^a12 include a methyl group, an ethyl group, a cyclohexyl group, a methylcyclohexyl group, a hydroxycyclohexyl group, an oxocyclohexyl group, and an adamantyl group. Examples of the saturated cyclic hydrocarbon group formed by R ^a10 , R ^a11 and the carbon to which they are bonded include a cyclohexyl group and an adamantyl group.

  Examples of the monomer (a1-3) having a norbornene ring include, for example, 5-norbornene-2-carboxylic acid-tert-butyl, 5-norbornene-2-carboxylic acid 1-cyclohexyl-1-methylethyl, 5-norbornene-2 -1-methylcyclohexyl carboxylate, 2-methyl-2-adamantyl 5-norbornene-2-carboxylate, 2-ethyl-2-adamantyl 5-norbornene-2-carboxylate, 5-norbornene-2-carboxylic acid 1- (4-methylcyclohexyl) -1-methylethyl, 5-norbornene-2-carboxylic acid 1- (4-hydroxycyclohexyl) -1-methylethyl, 5-norbornene-2-carboxylic acid 1-methyl-1- (4 -Oxocyclohexyl) ethyl, 5-norbornene-2-carboxylic acid 1- (1-adap Pentyl) -1-methylethyl and the like.

  The content of the structural unit derived from the monomer represented by the formula (a1-3) in the resin is usually 10 to 95 mol%, preferably 15 to 90 mol%, more preferably in all units of the resin. Is 20 to 85 mol%.

［式（ａ１−４）中、Ｒ¹⁰は、水素原子、ハロゲン原子又はハロゲン原子を有してもよいＣ_1-6アルキル基を表す。
Ｒ¹¹は、それぞれ独立に、ハロゲン原子、水酸基、Ｃ_1-6アルキル基、Ｃ_1-6アルコキシ基、Ｃ_2-4アシル基、Ｃ_2-4アシルオキシ基、アクリロイル基又はメタクリロイル基を表す。
ｌ^ａは０〜４の整数を表す。ｌ^ａが２以上の整数である場合、複数のＲ¹¹は同一の種類の基であっても異なる種類の基であってもよい。
Ｒ¹²及びＲ¹³はそれぞれ独立に、水素原子又はＣ_1-12炭化水素基を表す。
Ｘ^ａ２は、単結合又は置換基を有していてもよいＣ_1-17飽和炭化水素基を表し、該飽和炭化水素基に含まれる−ＣＨ_２−は−ＣＯ−、−Ｏ−、−Ｓ−、−ＳＯ_２−又は−Ｎ（Ｒ^ｃ）−で置き換わっていてもよい。Ｒ^ｃは、水素原子又はＣ_1-6アルキル基を表す。
Ｙ^ａ３は、Ｃ_1-12脂肪族炭化水素基、Ｃ_3-18飽和環状炭化水素基又はＣ_6-18芳香族炭化水素基であり、該脂肪族炭化水素基、飽和環状炭化水素基及び芳香族炭化水素基は、置換基を有していてもよい。］ Examples of the monomer having the acid labile group (1) and the carbon-carbon double bond include a monomer (a1-4) represented by the formula (a1-4).

[In formula (a1-4), R ¹⁰ represents a hydrogen atom, a halogen atom or a C _1-6 alkyl group which may have a halogen atom.
R ¹¹ each independently represents a halogen atom, a hydroxyl group, a C _1-6 alkyl group, a C _1-6 alkoxy group, a C _2-4 acyl group, a C _2-4 acyloxy group, an acryloyl group or a methacryloyl group.
l ^a represents an integer of 0 to 4; If l ^a is an integer of 2 or more, plural R ¹¹ may be the same kind a group even if different types of groups.
R ¹² and R ¹³ each independently represents a hydrogen atom or a C _1-12 hydrocarbon group.
X ^a2 represents a C _1-17 saturated hydrocarbon group which may have a single bond or a substituent, and —CH ₂ — contained in the saturated hydrocarbon group represents —CO—, —O—, —S. -, - SO ₂ - or -N ^{(R c)} - may be replaced by. R ^c represents a hydrogen atom or a C _1-6 alkyl group.
Y ^a3 is a C _1-12 aliphatic hydrocarbon group, a C _3-18 saturated cyclic hydrocarbon group or a C _6-18 aromatic hydrocarbon group, and the aliphatic hydrocarbon group, saturated cyclic hydrocarbon group and aromatic The group hydrocarbon group may have a substituent. ]

Ｃ_6-18芳香族炭化水素基としては、例えば、フェニル基、ナフチル基、アントニル基、ｐ−メチルフェニル基、ｐ−ｔｅｒｔ−ブチルフェニル基、ｐ−アダマンチルフェニル基等が挙げられる。 Examples of the C _1-6 alkyl group which may have a halogen atom include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butyl group, a perfluorotert-butyl group, A perfluoropentyl group, a perfluorohexyl group, etc. are mentioned. Q ¹ and Q ² are each independently preferably a perfluoromethyl group or a fluorine atom, more preferably a fluorine atom.
Examples of the C _1-6 alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group. A C _1-4 alkyl group is preferred, a C _1-2 alkyl group is more preferred, and a methyl group is particularly preferred.
Examples of the C _1-6 alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentoxy group, and an n-hexoxy group. A C _1-4 alkoxy group is preferable, a C _1-2 alkoxy group is more preferable, and a methoxy group is particularly preferable.
Examples of the C _2-4 acyl group include acetyl, propionyl, butyryl and the like.
Examples of the C _2-4 acyloxy group include acetyloxy, propionyloxy, butyryloxy and the like.
Examples of the C _1-12 hydrocarbon group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, Examples include 2-ethylhexyl group, cyclohexyl group, adamantyl group, 2-alkyl-2-adamantyl group, 1- (1-adamantyl) -1-alkyl group, isobornyl group and the like.
Examples of the C _1-12 aliphatic hydrocarbon group include a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, n- Examples include hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl and the like.
Examples of the C _3-18 saturated cyclic hydrocarbon group include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, norbornyl group, 1-adamantyl group, 2 -Adamantyl group, isobornyl group, group shown below, etc. are mentioned.

Examples of the C _6-18 aromatic hydrocarbon group include a phenyl group, a naphthyl group, an antonyl group, a p-methylphenyl group, a p-tert-butylphenyl group, and a p-adamantylphenyl group.

  As a monomer (a1-4), the following monomers are mentioned, for example.

  The content of the structural unit derived from the monomer represented by the formula (a1-4) in the resin is usually 10 to 95 mol%, preferably 15 to 90 mol%, more preferably in all units of the resin. Is 20 to 85 mol%.

The resin (A) is preferably a co-polymerization of a monomer (a1) having an acid labile group and a monomer having no acid labile group (hereinafter sometimes referred to as “acid stable monomer”). It is a coalescence. An acid stable monomer may be used individually by 1 type, and may use 2 or more types together.
When the resin (A) is a copolymer of a monomer (a1) having an acid labile group and an acid stable monomer, the structural units derived from the monomer (a1) having an acid labile group are all Preferably it is 10-80 mol% with respect to 100 mol% of structural units, More preferably, it is 20-60 mol%. Further, the structural unit derived from the monomer having an adamantyl group (particularly the monomer (a1-1) having an acid labile group) is added in an amount of 15 mol with respect to 100 mol% of the monomer (a1) having an acid labile group. % Or more is preferable. When the ratio of the monomer having an adamantyl group increases, the dry etching resistance of the resist is improved.

  As the acid stable monomer, those having a hydroxy group or a lactone ring are preferred. Derived from an acid stable monomer having a hydroxy group (hereinafter referred to as “acid stable monomer having a hydroxy group (a2)”) or an acid stable monomer having a lactone ring (hereinafter referred to as “acid stable monomer having a lactone ring (a3)”) If a resin having a structural unit to be used is used, the resolution of the resist and the adhesion to the substrate can be improved.

<Acid-stable monomer having a hydroxy group (a2)>
When the resist composition is used for KrF excimer laser exposure (248 nm), high energy beam exposure such as electron beam or EUV light, the acid-stable monomer (a2) having a hydroxy group has an acid having a phenolic hydroxyl group which is a hydroxystyrene. It is preferable to use a stable monomer (a2-0). When using short wavelength ArF excimer laser exposure (193 nm) or the like, an acid stable monomer having a hydroxyadamantyl group represented by formula (a2-1) should be used as the acid stable monomer having a hydroxy group (a2). Is preferred. The acid-stable monomer (a2) having a hydroxy group may be used alone or in combination of two or more.

  Examples of the monomer (a2-0) having a phenolic hydroxyl group include styrene monomers such as p- or m-hydroxystyrene represented by the formula (a2-0).

［式（ａ２−０）中、
Ｒ^８は、水素原子、ハロゲン原子又はハロゲン原子を有してもよいＣ_1-6アルキル基を表す。
Ｒ^９は、ハロゲン原子、水酸基、Ｃ_1-6アルキル基、Ｃ_1-6アルコキシ基、Ｃ_2-4アシル基、Ｃ_2-4アシルオキシ基、アクリロイル基又はメタクリロイル基を表す。
ｍａは０〜４の整数を表す。ｍａが２以上の整数である場合、複数のＲ^９は同一の種類の基であっても異なる種類の基であってもよい。］

[In the formula (a2-0),
R ⁸ represents a hydrogen atom, a halogen atom or a C _1-6 alkyl group which may have a halogen atom.
R ⁹ represents a halogen atom, a hydroxyl group, a C _1-6 alkyl group, a C _1-6 alkoxy group, a C _2-4 acyl group, a C _2-4 acyloxy group, an acryloyl group or a methacryloyl group.
ma represents an integer of 0 to 4. When ma is an integer of 2 or more, the plurality of R ⁹ may be the same type of group or different types of groups. ]

Examples of the C _1-6 alkyl group which may have a halogen atom include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butyl group, a perfluorotert-butyl group, A perfluoropentyl group, a perfluorohexyl group, etc. are mentioned. Q ¹ and Q ² are each independently preferably a perfluoromethyl group or a fluorine atom, more preferably a fluorine atom.
Examples of the C _1-6 alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group. A C _1-4 alkyl group is preferred, a C _1-2 alkyl group is more preferred, and a methyl group is particularly preferred.
Examples of the C _1-6 alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentoxy group, and an n-hexoxy group. A C _1-4 alkoxy group is preferable, a C _1-2 alkoxy group is more preferable, and a methoxy group is particularly preferable.
Examples of the C _2-4 acyl group include acetyl, propionyl, butyryl and the like.
Examples of the C _2-4 acyloxy group include acetyloxy, propionyloxy, butyryloxy and the like.

When obtaining a copolymer resin having a structural unit derived from a monomer having such a phenolic hydroxyl group, the corresponding (meth) acrylic acid ester monomer, acetoxystyrene, and styrene are radically polymerized and then deacetylated with an acid. Can be obtained.
Examples of the monomer having a phenolic hydroxyl group include the following monomers.

  Of the above monomers, 4-hydroxystyrene or 4-hydroxy-α-methylstyrene is particularly preferred.

  The content of the structural unit derived from the monomer represented by the formula (a2-0) in the resin is usually from 5 to 90 mol%, preferably from 10 to 85 mol%, more preferably in all units of the resin. Is 15 to 80 mol%.

  Examples of the acid stable monomer having a hydroxyadamantyl group include a monomer represented by the formula (a2-1).

In formula (a2-1), L ^a3 represents —O— or —O— (CH ₂ ) _k2 —CO—O—, and k2 represents an integer of 1 to 7. R ^a14 represents a hydrogen atom or a methyl group. R ^a15 and R ^a16 each independently represent a hydrogen atom, a methyl group or a hydroxy group. o1 represents an integer of 0 to 10.

L ^a3 is preferably —O—, —O— (CH ₂ ) _f1 —CO—O— (wherein f1 is an integer of 1 to 4), and more preferably —O—. R ^a14 is preferably a methyl group. R ^a15 is preferably a hydrogen atom. R ^a16 is preferably a hydrogen atom or a hydroxy group. o1 is preferably an integer of 0 to 3, more preferably 0 or 1.

  Examples of the acid-stable monomer (a2-1) having a hydroxyadamantyl group include the following. Among these, 3-hydroxy-1-adamantyl (meth) acrylate, 3,5-dihydroxy-1-adamantyl ( 1- (3,5-dihydroxy-1-adamantyloxycarbonyl) methyl (meth) acrylate and (meth) acrylate are preferred, and 3-hydroxy-1-adamantyl (meth) acrylate and 3,5-dihydroxy-1-adamantyl ( (Meth) acrylate is more preferable, and 3-hydroxy-1-adamantyl methacrylate and 3,5-dihydroxy-1-adamantyl methacrylate are more preferable.

  The content of the structural unit derived from the monomer represented by the formula (a2-1) in the resin is usually from 3 to 45 mol%, preferably from 5 to 40 mol%, more preferably in all units of the resin. Is 5 to 35 mol%.

<Acid-stable monomer having a lactone ring (a3)>
The lactone ring possessed by the acid-stable monomer (a3) may be a monocycle such as a β-propiolactone ring, γ-butyrolactone ring, or δ-valerolactone ring, or a monocyclic lactone ring and other rings. The condensed ring may be used. Among these lactone rings, a γ-butyrolactone ring and a condensed ring of a γ-butyrolactone ring and another ring are preferable.

  The acid stable monomer (a3) having a lactone ring is preferably represented by the formula (a3-1), the formula (a3-2) or the formula (a3-3). These 1 type may be used independently and may use 2 or more types together.

In formulas (a3-1) to (a3-3), L ^{a4 to} L ^a6 each independently represent —O— or —O— (CH ₂ ) _k3 —CO—O—, and k3 represents 1 to An integer of 7 is represented. R ^{a18 to} R ^a20 each independently represents a hydrogen atom or a methyl group. R ^a21 represents a C _1-4 aliphatic hydrocarbon group, and p1 represents an integer of 0 to 5. R ^a22 and R ^a23 each independently represent a carboxy group, a cyano group or a C _1-4 aliphatic hydrocarbon group, and q1 and r1 each independently represent an integer of 0 to 3. When p1, q1 or r1 is 2 or more, a plurality of R ^a21 , R ^a22 or R ^a23 may be the same as or different from each other.

Examples of L ^{a4 to} L ^a6 include those described for L ^a3 . L ^{a4 to} L ^a6 are each independently preferably —O—, —O— (CH ₂ ) _d1 —CO—O— (wherein d1 is an integer of 1 to 4), more preferably -O-. However, —O— and the like enumerated in L ^{a4 to} L ^a6 mean that they are bonded to —CO— of the formula (a3-1) to the formula (a3-3) on the left side and to the lactone ring on the right side. To do. R ^{a18 to} R ^a20 are preferably methyl groups. R ^a21 is preferably a methyl group. R ^a22 and R ^a23 are each independently preferably a carboxy group, a cyano group or a methyl group. p1 to r1 are each independently preferably 0 to 2, more preferably 0 or 1.

  Examples of the acid stable monomer (a3-1) having a γ-butyrolactone ring include the following.

  As the acid stable monomer (a3-1) having a γ-butyrolactone ring, an acid labile monomer can also be exemplified. For example, the following are mentioned.

  Examples of the acid stable monomer (a3-2) having a condensed ring of γ-butyrolactone ring and norbornane ring include the following.

  As the acid stable monomer (a3-2) having a condensed ring of γ-butyrolactone ring and norbornane ring, an acid labile monomer can be exemplified. For example, the following are mentioned.

  Examples of the acid stable monomer (a3-3) having a condensed ring of γ-butyrolactone ring and cyclohexane ring include the following.

  An acid labile monomer can also be exemplified as the monomer (a3-3) having a condensed ring of γ-butyrolactone ring and cyclohexane ring. For example, the following are mentioned.

Among acid-stable monomers (a3) having a lactone ring, (meth) acrylic acid (5-oxo-4-oxatricyclo [4.2.1.0 ^3,7 ] nonan-2-yl, (meth) acrylic Acid tetrahydro-2-oxo-3-furyl, 2- (5-oxo-4-oxatricyclo [4.2.1.0 ^3,7 ] nonan-2-yloxy) -2-oxoethyl (meth) acrylate Are preferred, and those in the form of methacrylate are more preferred.

  Content of the structural unit derived from the monomer represented by Formula (a3-1), Formula (a3-2) or Formula (a3-3) in the resin is usually 5 to 70 mol% in all units of the resin. Yes, preferably 10 to 65 mol%, more preferably 10 to 60 mol%.

<Other acid stable monomers (a4)>
Examples of the other acid stable monomer (a4) include maleic anhydride represented by formula (a4-1), itaconic anhydride represented by formula (a4-2), and formula (a4-3). And acid-stable monomers having a norbornene ring.

In formula (a4-3), R ^a25 and R ^a26 each independently represent a hydrogen atom, a C _1-3 aliphatic hydrocarbon group ^optionally having a substituent (for example, a hydroxy group), a cyano group, or a carboxy group. R ^a25 and R ^a26 are bonded to each other to form —CO—O—CO—, and R ^a27 is a C _1-36 aliphatic hydrocarbon group, or an alkoxycarbonyl group (—COOR ^a27 ), Alternatively, it represents a C _3-36 saturated cyclic hydrocarbon group, and —CH ₂ — in the aliphatic hydrocarbon group and saturated cyclic hydrocarbon group may be replaced by —O— or —CO—. However, those in which —COOR ^a27 is an acid labile group are excluded (that is, R ^a27 does not include those in which a tertiary carbon atom is bonded to —O—).

^Examples of the aliphatic hydrocarbon group which may have a substituent for R ^a25 and R ^a26 include a methyl group, an ethyl group, a propyl group, a hydroxymethyl group, and a 2-hydroxyethyl group. The carbon number of the aliphatic hydrocarbon group of R ^a27 is preferably 1 to 8, more preferably 1 to 6, and the saturated cyclic hydrocarbon group preferably has 4 to 36, more preferably 4 to 12 carbon atoms. is there. ^Examples of R ^a27 include a methyl group, an ethyl group, a propyl group, a 2-oxo-oxolan-3-yl group, and a 2-oxo-oxolan-4-yl group.

  Examples of the acid-stable monomer (a4-3) having a norbornene ring include 2-norbornene, 2-hydroxy-5-norbornene, 5-norbornene-2-carboxylic acid, methyl 5-norbornene-2-carboxylate, and 5-norbornene. Examples include 2-hydroxy-1-ethyl-2-carboxylate, 5-norbornene-2-methanol, 5-norbornene-2,3-dicarboxylic acid anhydride, and the like.

  Content of the structural unit derived from the monomer represented by Formula (a4-1), Formula (a4-2), or Formula (a4-3) in the resin is usually 2 to 40 mol% in all units of the resin. Yes, preferably 3-30 mol%, more preferably 5-20 mol%.

  A preferred resin (A) is a copolymer obtained by polymerizing at least a monomer (a1) having an acid labile group, an acid stable monomer (a2) having a hydroxy group, and / or an acid stable monomer (a3) having a lactone ring. It is a polymer. In this preferred copolymer, the monomer (a1) having an acid labile group is more preferably at least one of a monomer (a1-1) having an adamantyl group and a monomer (a1-2) having a cyclohexyl group. A species (more preferably a monomer (a1-1) having an adamantyl group), and an acid stable monomer (a2) having a hydroxy group, preferably an acid stable monomer (a2-1) having a hydroxyadamantyl group, and a lactone The acid-stable monomer (a3) having a ring is more preferably an acid-stable monomer (a3-1) having a γ-butyrolactone ring and an acid-stable monomer (a3-2) having a condensed ring of a γ-butyrolactone ring and a norbornane ring At least one of the following. Resin (A) can be manufactured by a well-known polymerization method (for example, radical polymerization method).

  The weight average molecular weight of the resin (A) is preferably 2,500 or more (more preferably 3,000 or more) and 50,000 or less (more preferably 30,000 or less).

  It is preferable that content of resin (A) is 80 mass% or more in solid content of a composition. In the present specification, the “solid content in the composition” means the total of the composition components excluding the solvent (E). The solid content in the composition and the content of the resin (A) relative thereto can be measured by known analytical means such as liquid chromatography or gas chromatography.

<Basic compound (hereinafter sometimes referred to as “basic compound (C)”)>
The resist composition of the present invention contains a basic compound (C). The content of the basic compound (C) is preferably about 0.01 to 1% by mass based on the solid content of the resist composition.

  The basic compound (C) is preferably a basic nitrogen-containing organic compound (for example, an amine) and an ammonium salt. The amine may be an aliphatic amine or an aromatic amine. As the aliphatic amine, any of primary amine, secondary amine and tertiary amine can be used. The aromatic amine may be any of an amino group bonded to an aromatic ring such as aniline and a heteroaromatic amine such as pyridine. Preferable basic compound (C) includes an aromatic amine represented by the formula (C2), particularly an aniline represented by the formula (C2-1).

In the formula (C2), Ar ^c1 represents an aromatic hydrocarbon group. R ^c5 and R ^c6 each independently represent a hydrogen atom, an aliphatic hydrocarbon group (preferably an alkyl group), a saturated cyclic hydrocarbon group (preferably a cycloalkyl group) or an aromatic hydrocarbon group. However, the hydrogen atom of the aliphatic hydrocarbon group, the saturated cyclic hydrocarbon group or the aromatic hydrocarbon group may be substituted with a hydroxy group, an amino group, or a C _1-6 alkoxy group, and the amino group _May be substituted with a C _1-4 alkyl group. The carbon number of the aliphatic hydrocarbon group is preferably about 1 to 6, the carbon number of the saturated cyclic hydrocarbon group is preferably about 5 to 10, and the carbon number of the aromatic hydrocarbon group is Preferably, it is about 6-10.

In formula (C2-1), R ^c5 and R ^c6 are the same as described above. R ^c7 represents an aliphatic hydrocarbon group (preferably an alkyl group), an alkoxy group, a saturated cyclic hydrocarbon group (preferably a cycloalkyl group) or an aromatic hydrocarbon group. However, the hydrogen atom of an aliphatic hydrocarbon group, an alkoxy group, a saturated cyclic hydrocarbon group, and an aromatic hydrocarbon group may have the substituent demonstrated by Formula (C2). m3 represents an integer of 0 to 3. When m3 is 2 or more, the plurality of R ^c7 may be the same as or different from each other. Aliphatic hydrocarbon group R ^c7, preferable number of carbon atoms of the saturated cyclic hydrocarbon group and the aromatic hydrocarbon group are the same as those of the formula (C2), the carbon number of the alkoxy group R ^c7 is independently in, preferably 1 It is about ~ 6.

  Examples of the aromatic amine (C2) include 1-naphthylamine and 2-naphthylamine. Examples of aniline (C2-1) include aniline, diisopropylaniline, 2-, 3- or 4-methylaniline, 4-nitroaniline, N-methylaniline, N, N-dimethylaniline, diphenylamine and the like. Of these, diisopropylaniline (particularly 2,6-diisopropylaniline) is preferable.

  Moreover, as a basic compound (C), the compound represented by Formula (C3)-Formula (C11) is mentioned.

R ^c8 in formula (C3) represents any of the groups described for R ^c7 in formula (C2). R ^c9 , R ^c10 , R ^{c11 to} R ^c14 , R ^{c16 to} R ^c19 and R ^c22 bonded to the nitrogen atom in formula (C3) to formula (C8) are each independently R ^{c5 in} formula (C2) and It represents one of the groups described for R ^c6 . R ^c20 , R ^c21 and R ^{c23 to} R ^c28 bonded to the aromatic carbon in formula (C7) to formula (C11) are each independently any group described for R ^c7 in formula (C2-1) Represents. O3 to u3 in Formula (C7) and Formula (C9) to Formula (C11) each independently represents an integer of 0 to 3. When any of o3 to u3 is 2 or more, any of the plurality of R ^{c20 to} R ^c28 may be the same as or different from each other.

R ^c15 in formula (C6) represents an aliphatic hydrocarbon group, a saturated cyclic hydrocarbon group, or an alkanoyl group, and n3 represents an integer of 0 to 8. When n3 is 2 or more, the plurality of R ^c15 may be the same as or different from each other. The number of carbon atoms of the aliphatic hydrocarbon group R ^c15 is preferably about 1 to 6 carbon atoms in the saturated cyclic hydrocarbon group R ^c15 is preferably about 3 to 6, alkanoyl group R ^c15 Preferably carbon number is about 2-6.

L ^c1 and L ^{c2 in} formula (C7) and formula (C10) are each independently a divalent aliphatic hydrocarbon group (preferably an alkylene group), —CO—, —C (═NH) —, —C (= NR ^c3 )-, -S-, -SS-, or a combination thereof. The divalent aliphatic hydrocarbon group preferably has about 1 to 6 carbon atoms. R ^c3 represents a C _1-4 alkyl group.

  Examples of the compound (C3) include hexylamine, heptylamine, octylamine, nonylamine, decylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, triethylamine, trimethylamine, tripropylamine, Tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, methyldibutylamine, methyldipentylamine, methyldihexylamine, methyldicyclohexylamine, methyldiheptylamine, methyldioctyl Amine, methyl dinonyl amine, methyl didecyl amine, ethyl dibutyl amine, ethyl dipentyl amine, ethyl di Silamine, ethyldiheptylamine, ethyldioctylamine, ethyldinonylamine, ethyldidecylamine, dicyclohexylmethylamine, tris [2- (2-methoxyethoxy) ethyl] amine, triisopropanolamine ethylenediamine, tetramethylenediamine, hexamethylene Examples include diamine, 4,4′-diamino-1,2-diphenylethane, 4,4′-diamino-3,3′-dimethyldiphenylmethane, 4,4′-diamino-3,3′-diethyldiphenylmethane, and the like.

  Examples of the compound (C4) include piperazine. Examples of the compound (C5) include morpholine. Examples of the compound (C6) include piperidine and hindered amine compounds having a piperidine skeleton described in JP-A No. 11-52575. Examples of the compound (C7) include 2,2′-methylenebisaniline.

  Examples of the compound (C8) include imidazole and 4-methylimidazole. Examples of the compound (C9) include pyridine and 4-methylpyridine. Examples of the compound (C10) include 1,2-di (2-pyridyl) ethane, 1,2-di (4-pyridyl) ethane, 1,2-di (2-pyridyl) ethene, and 1,2-di. (4-pyridyl) ethene, 1,3-di (4-pyridyl) propane, 1,2-di (4-pyridyloxy) ethane, di (2-pyridyl) ketone, 4,4′-dipyridyl sulfide, 4, 4'-dipyridyl disulfide, 2,2'-dipyridylamine, 2,2'-dipicolylamine and the like can be mentioned. Examples of the compound (C11) include bipyridine.

  As ammonium salts, tetramethylammonium hydroxide, tetraisopropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, phenyltrimethylammonium hydroxide, 3- (trifluoromethyl) phenyltrimethyl Examples include ammonium hydroxide, tetra-n-butylammonium salicylate, choline, and the like.

<Solvent (sometimes referred to as "solvent (E)")
The resist composition of the present invention may contain the solvent (E) in an amount of 90% by mass or more in the composition. The resist composition of the present invention containing the solvent (E) is suitable for producing a thin film resist. The content of the solvent (E) is 90% by mass or more (preferably 92% by mass or more, more preferably 94% by mass or more) and 99.9% by mass or less (preferably 99% by mass or less) in the composition. The content of the solvent (E) can be measured by a known analysis means such as liquid chromatography or gas chromatography.

  Examples of the solvent (E) include glycol ether esters such as ethyl cellosolve acetate, methyl cellosolve acetate and propylene glycol monomethyl ether acetate; glycol ethers such as propylene glycol monomethyl ether; ethyl lactate, butyl acetate, amyl acetate and And esters such as ethyl pyruvate; ketones such as acetone, methyl isobutyl ketone, 2-heptanone and cyclohexanone; cyclic esters such as γ-butyrolactone; A solvent (E) may be used individually by 1 type, and may use 2 or more types together.

<Other components (hereinafter sometimes referred to as “other components (F)”)>
The resist composition of this invention may contain the other component (F) as needed. Component (F) is not particularly limited, and additives known in the resist field, such as sensitizers, dissolution inhibitors, surfactants, stabilizers, dyes, and the like can be used.

<Method for producing resist pattern>
The method for producing a resist pattern of the present invention comprises:
(1) The process of apply | coating the resist composition of this invention mentioned above on a board | substrate,
(2) The process of drying the composition after application | coating and forming a composition layer,
(3) a step of exposing the composition layer using an exposure machine;
(4) A step of heating the composition layer after exposure,
(5) The process which develops the composition layer after a heating using a image development apparatus is included.

  Application of the resist composition onto the substrate can be performed by a commonly used apparatus such as a spin coater.

The composition after application | coating is dried and the solvent contained in a composition is removed. The removal of the solvent is performed, for example, by evaporating the solvent using a heating device such as a hot plate or by using a decompression device to form a composition layer from which the solvent has been removed. As for the temperature in this case, about 50-200 degreeC is illustrated, for example. The pressure is exemplified by about 1 to 1.0 × 10 ⁵ Pa.

The obtained composition layer is exposed using an exposure machine. At this time, exposure is usually performed through a mask corresponding to a required pattern. The exposure light source emits ultraviolet laser light such as KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), F ₂ laser (wavelength 157 nm), solid-state laser light source (YAG or semiconductor laser, etc.) Various types of laser beam can be used, such as those that convert the wavelength of the laser beam from) to radiate a harmonic laser beam in the far ultraviolet region or the vacuum ultraviolet region.

The composition layer after the exposure is subjected to heat treatment for promoting the deprotection group reaction. As heating temperature, it is about 50-200 degreeC normally, Preferably it is about 70-150 degreeC.
The heated composition layer is usually developed using an alkali developer using a developing device.
The alkaline developer used here may be various alkaline aqueous solutions used in this field. Examples thereof include an aqueous solution of tetramethylammonium hydroxide and (2-hydroxyethyl) trimethylammonium hydroxide (commonly called choline).
After development, it is preferable to rinse with ultrapure water to remove water remaining on the substrate and the pattern.

<Application>
The composition of the present invention is useful for a photoresist composition, particularly a chemically amplified photoresist composition, and is used for fine processing of semiconductors, manufacture of circuit boards such as liquid crystals and thermal heads, and other photofabrication processes. It can be suitably used for a wide range of applications. In particular, it can be used as a chemically amplified photoresist composition suitable for excimer laser lithography such as ArF and KrF, ArF immersion exposure lithography, EB exposure lithography, and EUV exposure lithography. In addition to immersion exposure, it can also be used for dry exposure. Furthermore, it can be used for double imaging and is industrially useful.

Hereinafter, the present invention will be described in detail by way of examples.
In Examples and Comparative Examples, “%” and “part” representing content and use amount are based on mass unless otherwise specified.
The weight average molecular weight is a value obtained by gel permeation chromatography (HLC-8120GPC, manufactured by Tosoh Corporation, three columns are “TSKgel Multipore HXL-M”, and the solvent is tetrahydrofuran) using polystyrene as a standard product.
Column: TSKgel Multipore H _XL -M x 3 + guardcolumn (manufactured by Tosoh Corporation)
Eluent: Tetrahydrofuran Flow rate: 1.0 mL / min
Detector: RI detector Column temperature: 40 ° C
Injection volume: 100 μl
Molecular weight standard: Standard polystyrene (manufactured by Tosoh Corporation)

Example 1: Synthesis of a salt represented by the formula (B1)

  A flask equipped with a thermometer and a stirrer was charged with 5.78 parts of sodium hydride and 15.00 parts of tetrahydrofuran, and stirred at 0 ° C. for 30 minutes. To the obtained mixture, a mixed solution of 11.00 parts of a compound represented by the formula (B1-a) (5-hydroxy-2-adamantanone, manufactured by Tokyo Chemical Industry) and 40.00 parts of tetrahydrofuran was added at 0 ° C. for 2 hours. And added at 0 ° C. for 1 hour. To the obtained mixture, 8.50 parts of methoxymethyl chloride was further added at 0 ° C. over 40 minutes, and the mixture was stirred at 0 ° C. for 2 hours. To the obtained mixture, 55.00 parts of ion-exchanged water and 220.00 parts of ethyl acetate were added, and liquid separation was performed to recover the organic layer. To the recovered organic layer, 55.00 parts of ion exchange water was added, and liquid separation was performed to recover the organic layer. The collected organic layer was concentrated to obtain 14.03 parts of a compound represented by the formula (B1-b).

To a flask equipped with a thermometer and a stirrer, 6.00 parts of tetrahydrofuran, 1.67 parts of lithium chloride and 0.41 parts of zinc chloride were added and stirred at room temperature for 30 minutes. To the obtained mixture, 40.76 ml of ethylmagnesium chloride was added at 23 ° C. over 1 hour, and then cooled to 0 ° C. to give 6.00 parts of the compound represented by the formula (B1-b) and tetrahydrofuran 12.00. Part of the mixed solution was added over 1 hour and further stirred at 0 ° C. for 30 minutes. To the obtained mixture, 1.60 parts of acetic acid was added and stirred for 30 minutes. After concentrating the obtained mixture, 36.00 parts of ethyl acetate and 12.00 parts of a saturated aqueous ammonium chloride solution were added, and liquid separation was performed to recover the organic layer. To the recovered organic layer, 12.00 parts of ion-exchanged water was added, and liquid separation was performed to recover the organic layer. The washing operation was performed 3 times. To the collected organic layer, 1.00 part of magnesium sulfate was added, stirred and filtered. The collected filtrate layer was concentrated and fractionated in a column under the following conditions to obtain 5.00 parts of a compound represented by the formula (B1-c).
Developing medium; silica gel 60-200 mesh; manufactured by Merck developing solvent: n-heptane / ethyl acetate = 1/1 (volume ratio)

  2. 5.00 parts of a compound represented by the formula (B1-d) obtained by the method described in JP-A-2008-13551, 30.00 parts of chloroform, a compound represented by the formula (B1-c) 12 parts, molecular sieve (trade name: Molecular sieve 5A, manufactured by Wako Pure Chemical Industries, Ltd.) 7.00 part and lithium amide 0.14 part were charged, heated to reflux at 80 ° C. for 120 hours, and then filtered. The obtained filtrate was charged with 0.28 part of oxalic acid and 7.50 parts of ion-exchanged water, and stirred and separated. Water washing was performed 6 times. The obtained organic layer was charged with 1.00 part of activated carbon, stirred at 23 ° C. for 30 minutes, and then filtered. After the filtrate was concentrated, 6.88 parts of acetonitrile was added to the resulting concentrate to dissolve it, concentrated, 10 parts of ethyl acetate was added and stirred, and the supernatant was removed. To the obtained residue, 10 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. The obtained residue was dissolved in chloroform and concentrated to obtain 0.22 part of a salt represented by the formula (B1) as an oily substance.

MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (-) Spectrum): M ^- 397.1

Example 2: Synthesis of a salt represented by the formula (B2)

  In a flask equipped with a thermometer and a stirrer, 40.00 parts of a compound represented by the formula (B1-a) (5-hydroxy-2-adamantanone, manufactured by Tokyo Chemical Industry), 200.00 parts of tetrahydrofuran, 4-dimethyl Aminopyridine (DMAP): 43.58 parts were charged and dissolved at room temperature with stirring. To the mixture, 67.47 parts of di-tert-butyl dicarbonate was added dropwise and stirred at 40 ° C. for 5 hours. Further, 12.06 parts of concentrated hydrochloric acid was added. After stirring for 30 minutes, 400.00 parts of ethyl acetate was added and stirred, followed by liquid separation. 100.00 parts of ion-exchanged water was added to the organic layer, followed by liquid separation washing, and further, a mixed solution of 12.06 parts of concentrated hydrochloric acid and 100.00 parts of ion-exchanged water was added to the organic layer for washing. Further, the organic layer was separated and washed with 100.00 parts of ion-exchanged water, and then the organic layer was concentrated. Compound 21 represented by the formula (B2-b) is obtained by fractionating the concentrated mass into a column (Kanto Kagaku Silica Gel 60N (spherical, neutral) 100-210 μm developing solvent: n-heptane / ethyl acetate = 5/1). .53 parts were obtained.

To a flask equipped with a thermometer and a stirrer, 6.00 parts of tetrahydrofuran, 1.67 parts of lithium chloride and 0.41 parts of zinc chloride were added and stirred at room temperature for 30 minutes. To the obtained mixture, 40.76 ml of ethylmagnesium chloride was added at 23 ° C. over 1 hour, then cooled to 0 ° C., 7.60 parts of the compound represented by formula (B2-b) and tetrahydrofuran 15.00. Part of the mixed solution was added over 1 hour, and the mixture was further stirred at 0 ° C. for 30 minutes. To the obtained mixture, 1.60 parts of acetic acid was added and stirred for 30 minutes. After concentrating the obtained mixture, 40.00 parts of ethyl acetate and 13.33 parts of a saturated aqueous ammonium chloride solution were added, liquid separation was performed, and the organic layer was recovered. To the recovered organic layer, 13.33 parts of ion-exchanged water was added, and liquid separation was performed to recover the organic layer. The washing operation was performed 3 times. To the collected organic layer, 1.00 part of magnesium sulfate was added, stirred and filtered. The collected filtrate layer was concentrated and fractionated in a column under the following conditions to obtain 5.59 parts of a compound represented by the formula (B2-c).
Developing medium: silica gel 60-200 mesh; manufactured by Merck developing solvent: n-heptane / ethyl acetate = 2/1 (volume ratio)

  2. 5.00 parts of a compound represented by the formula (B1-d) obtained by the method described in JP-A-2008-13551, 30.00 parts of chloroform, a compound represented by the formula (B2-c) 85 parts, molecular sieve (trade name: Molecular sieve 5A, manufactured by Wako Pure Chemical Industries, Ltd.) 7.00 part and lithium amide 0.14 part were charged, heated to reflux at 80 ° C. for 120 hours, and then filtered. The obtained filtrate was charged with 0.30 part of oxalic acid and 8.00 part of ion-exchanged water, and stirred and separated. Water washing was performed 8 times. The obtained organic layer was charged with 1.00 part of activated carbon, stirred at 23 ° C. for 30 minutes, and then filtered. After the filtrate was concentrated, 7.50 parts of acetonitrile was added and dissolved in the resulting concentrate, concentrated, 10 parts of ethyl acetate was added and stirred, and the supernatant was removed. To the obtained residue, 10 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. The obtained residue was dissolved in chloroform and concentrated to obtain 0.35 part of a salt represented by the formula (B2) as an oily substance.

MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (-) Spectrum): M ^- 453.1

式（Ｂ３−ｄ）で表される化合物５．４６部、クロロホルム４０．００部、式（Ｂ１−ｃ）で表される化合物３．１２部、モレキュラーシーブ（商品名：モレキュラーシーブ ５Ａ、和光純薬製）７．００部及びリチウムアミド０．１４部を仕込み、８０℃で１２０時間加熱還流した後、ろ過した。得られたろ液に、シュウ酸０．２８部及びイオン交換水７．５０部を仕込み、攪拌、分液を行った。水洗を６回行った。得られた有機層に活性炭１．００部を仕込み、２３℃で３０分間攪拌した後、ろ過した。ろ液を濃縮した後、得られた濃縮物に、アセトニトリル６．８８部を添加して溶解し、濃縮し、酢酸エチル１０部を加えて攪拌し、上澄液を除去した。得られた残渣にｔｅｒｔ−ブチルメチルエーテル１０部を加えて攪拌し、上澄液を除去した。得られた残渣をクロロホルムに溶解し、濃縮して、式（Ｂ３）で表される塩０．３２部を得た。 Example 3: Synthesis of a salt represented by the formula (B3)

5.46 parts of the compound represented by the formula (B3-d), 40.00 parts of chloroform, 3.12 parts of the compound represented by the formula (B1-c), molecular sieve (trade name: Molecular sieve 5A, Jun Wako) (Product made from medicine) 7.00 part and 0.14 part of lithium amide were prepared, and it heated and refluxed at 80 degreeC for 120 hours, It filtered. The obtained filtrate was charged with 0.28 part of oxalic acid and 7.50 parts of ion-exchanged water, and stirred and separated. Water washing was performed 6 times. The obtained organic layer was charged with 1.00 part of activated carbon, stirred at 23 ° C. for 30 minutes, and then filtered. After the filtrate was concentrated, 6.88 parts of acetonitrile was added to the resulting concentrate to dissolve it, concentrated, 10 parts of ethyl acetate was added and stirred, and the supernatant was removed. To the obtained residue, 10 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. The obtained residue was dissolved in chloroform and concentrated to obtain 0.32 parts of the salt represented by the formula (B3).

MS (ESI (+) Spectrum): M ⁺ 305.1
MS (ESI (-) Spectrum): M ^- 397.1

式（Ｂ４−ｄ）で表される化合物５．１９部、クロロホルム４０．００部、式（Ｂ１−ｃ）で表される化合物３．１２部、モレキュラーシーブ（商品名：モレキュラーシーブ ５Ａ、和光純薬製）７．００部及びリチウムアミド０．１４部を仕込み、８０℃で１２０時間加熱還流した後、ろ過した。得られたろ液に、シュウ酸０．２８部及びイオン交換水７．５０部を仕込み、攪拌、分液を行った。水洗を６回行った。得られた有機層に活性炭１．００部を仕込み、２３℃で３０分間攪拌した後、ろ過した。ろ液を濃縮した後、得られた濃縮物に、アセトニトリル６．８８部を添加して溶解し、濃縮し、酢酸エチル１０部を加えて攪拌し、上澄液を除去した。得られた残渣にｔｅｒｔ−ブチルメチルエーテル１０部を加えて攪拌し、上澄液を除去した。得られた残渣をクロロホルムに溶解し、濃縮した後、得られた濃縮物をカラム（メルク シリカゲル６０−２００メッシュ 展開溶媒：クロロホルム／メタノール＝５／１）分取することにより、式（Ｂ４）で表される塩０．２５部を得た。 Example 4: Synthesis of salt represented by formula (B4)

5.19 parts of the compound represented by the formula (B4-d), 40.00 parts of chloroform, 3.12 parts of the compound represented by the formula (B1-c), molecular sieve (trade name: Molecular sieve 5A, Jun Wako) (Product made from medicine) 7.00 part and 0.14 part of lithium amide were prepared, and it heated and refluxed at 80 degreeC for 120 hours, Then, it filtered. The obtained filtrate was charged with 0.28 part of oxalic acid and 7.50 parts of ion-exchanged water, and stirred and separated. Water washing was performed 6 times. The obtained organic layer was charged with 1.00 part of activated carbon, stirred at 23 ° C. for 30 minutes, and then filtered. After the filtrate was concentrated, 6.88 parts of acetonitrile was added to the resulting concentrate to dissolve it, concentrated, 10 parts of ethyl acetate was added and stirred, and the supernatant was removed. To the obtained residue, 10 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. The obtained residue was dissolved in chloroform and concentrated, and the resulting concentrate was fractionated in a column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1) to obtain the formula (B4). 0.25 part of the salt represented was obtained.

MS (ESI (+) Spectrum): M ⁺ 281.0
MS (ESI (-) Spectrum): M ^- 397.1

式（Ｂ５−ｄ）で表される化合物４．３８部、クロロホルム４０．００部、式（Ｂ１−ｃ）で表される化合物３．１２部、モレキュラーシーブ（商品名：モレキュラーシーブ ５Ａ、和光純薬製）７．００部及びリチウムアミド０．１４部を仕込み、８０℃で１２０時間加熱還流した後、ろ過した。得られたろ液に、シュウ酸０．２８部及びイオン交換水７．５０部を仕込み、攪拌、分液を行った。水洗を６回行った。得られた有機層に活性炭１．００部を仕込み、２３℃で３０分間攪拌した後、ろ過した。ろ液を濃縮した後、得られた濃縮物に、アセトニトリル６．８８部を添加して溶解し、濃縮し、酢酸エチル１０部を加えて攪拌し、上澄液を除去した。得られた残渣にｔｅｒｔ−ブチルメチルエーテル１０部を加えて攪拌し、上澄液を除去した。得られた残渣をクロロホルムに溶解し、濃縮した後、得られた濃縮物をカラム（メルク シリカゲル６０−２００メッシュ 展開溶媒：クロロホルム／メタノール＝５／１）分取することにより、式（Ｂ５）で表される塩０．２２部を得た。 Example 5: Synthesis of salt represented by formula (B5)

4.38 parts of the compound represented by the formula (B5-d), 40.00 parts of chloroform, 3.12 parts of the compound represented by the formula (B1-c), molecular sieve (trade name: Molecular sieve 5A, Jun Wako) (Product made from medicine) 7.00 part and 0.14 part of lithium amide were prepared, and it heated and refluxed at 80 degreeC for 120 hours, It filtered. The obtained filtrate was charged with 0.28 part of oxalic acid and 7.50 parts of ion-exchanged water, and stirred and separated. Water washing was performed 6 times. The obtained organic layer was charged with 1.00 part of activated carbon, stirred at 23 ° C. for 30 minutes, and then filtered. After the filtrate was concentrated, 6.88 parts of acetonitrile was added to the resulting concentrate to dissolve it, concentrated, 10 parts of ethyl acetate was added and stirred, and the supernatant was removed. To the obtained residue, 10 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. The obtained residue was dissolved in chloroform and concentrated, and the resulting concentrate was fractionated in a column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1) to obtain the formula (B5). 0.22 parts of the salt represented were obtained.

MS (ESI (+) Spectrum): M ^<+> 207.1
MS (ESI (-) Spectrum): M ^- 397.1

Example 6: Synthesis of salt represented by formula (B6)

First, 36.14 parts of the compound represented by the formula (B1-c) and 200 parts of tetrahydrofuran were charged, stirred at room temperature, and after confirming the dissolution of the compound represented by the formula (B1-c), 14.27 parts of pyridine were charged. The temperature was raised to 40 ° C. Further, a mixed solution of 25.47 parts of chloroacetyl chloride and 50 parts of tetrahydrofuran was added dropwise over 1 hour. After dropping, the mixture was stirred at 40 ° C. for 5 hours, and the temperature was lowered to 5 ° C. 100 parts of ion-exchanged water cooled to 5 ° C. was added and stirred, and the aqueous layer was recovered by liquid separation. To the recovered aqueous layer, 100 parts of ethyl acetate was added and the layers were separated to recover the organic layer. 100 parts of 10% potassium carbonate aqueous solution at 5 ° C. is added to the collected organic layer for washing, liquid separation is performed to collect the organic layer, and then 100 parts of ion-exchanged water is further added to the collected organic layer. The organic layer was recovered by washing with water and liquid separation. This washing operation was repeated 3 times. After the collected organic layer was concentrated, 12.33 parts of a compound represented by the formula (B6-a) was obtained by fractionating the column under the following conditions.
Developing medium: silica gel 60-200 mesh; manufactured by Merck developing solvent: n-heptane / ethyl acetate = 2/1 (volume ratio)

式（Ｂ６−ｂ）で表される化合物８．１０部及びジメチルホルムアミド４１．８７部を仕込み、２３℃で３０分間攪拌した。得られた混合物に、炭酸カリウム２．５５部及びヨウ化カリウム０．７７部を仕込み、４０℃で１時間撹拌した後、式（Ｂ６−ａ）で表される化合物５．００部をジメチルホルムアミド９．７４部に溶解した溶液を１時間かけて滴下した。４０℃で６時間撹拌した後、２３℃に冷却した。得られた反応物に、クロロホルム２７２．１０部、５％シュウ酸水溶液４６．５１部及びイオン交換水２１．５２部を仕込み、攪拌、分液を行った。回収された有機層に、イオン交換水１０８．８４部を仕込み、攪拌、分液を行った。水洗を７回行った。得られた有機層に活性炭２．００部を仕込み、２３℃で３０分間攪拌した後、ろ過した。ろ液を濃縮した後、得られた濃縮物に、アセトニトリル５０部を添加して溶解し、濃縮し、酢酸エチル３０部を加えて攪拌し、上澄液を除去した。得られた残渣にｔｅｒｔ−ブチルメチルエーテル３０部を加えて攪拌し、上澄液を除去した。得られた残渣をクロロホルムに溶解し、濃縮した後、得られた濃縮物をカラム（メルク シリカゲル６０−２００メッシュ 展開溶媒：クロロホルム／メタノール＝５／１）分取することにより、式（Ｂ６）で表される塩６．１８部を得た。

8.10 parts of the compound represented by the formula (B6-b) and 41.87 parts of dimethylformamide were charged and stirred at 23 ° C. for 30 minutes. To the obtained mixture, 2.55 parts of potassium carbonate and 0.77 parts of potassium iodide were added and stirred at 40 ° C. for 1 hour, and then 5.00 parts of the compound represented by the formula (B6-a) was added to dimethylformamide. The solution dissolved in 9.74 parts was added dropwise over 1 hour. After stirring at 40 ° C. for 6 hours, the mixture was cooled to 23 ° C. To the obtained reaction product, 272.10 parts of chloroform, 46.51 parts of 5% oxalic acid aqueous solution and 21.52 parts of ion-exchanged water were added, and the mixture was stirred and separated. Into the collected organic layer, 108.84 parts of ion-exchanged water was charged, and stirred and separated. Washing with water was performed 7 times. The obtained organic layer was charged with 2.00 parts of activated carbon, stirred at 23 ° C. for 30 minutes, and then filtered. After the filtrate was concentrated, 50 parts of acetonitrile was added to the resulting concentrate to dissolve it, concentrated, 30 parts of ethyl acetate was added and stirred, and the supernatant was removed. To the obtained residue, 30 parts of tert-butyl methyl ether was added and stirred, and the supernatant was removed. The obtained residue is dissolved in chloroform and concentrated, and then the obtained concentrate is fractionated in a column (Merck silica gel 60-200 mesh developing solvent: chloroform / methanol = 5/1) to obtain the formula (B6). 6.18 parts of the salt represented were obtained.

MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (-) Spectrum): M ^- 455.1

Synthesis Example 1: Synthesis of Resin A1 A monomer represented by monomer E, a monomer represented by monomer F, a monomer represented by monomer B, a monomer represented by monomer C, and a monomer represented by monomer D Charged at a ratio of 30: 14: 6: 20: 30. Subsequently, 1.5 mass times dioxane was added with respect to the total mass of all the monomers. Into the obtained mixture, azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) as initiators were respectively added to 1.00 mol% and 3.00 mol% with respect to the total number of moles of all monomers. And heated at 73 ° C. for about 5 hours. Thereafter, the reaction solution is purified by performing the operation of pouring into a large amount of methanol / water mixed solvent (4: 1) and precipitating three times, and the weight average molecular weight is about 8.1 × 10 ^3. The coalescence was obtained with a yield of 65%. The obtained copolymer has a structural unit derived from each monomer of the following formula, and this was designated as resin A1.

Synthesis Example 2: Synthesis of Resin A2 A monomer represented by monomer A, a monomer represented by monomer B, and a monomer represented by monomer C were charged in a molar ratio of 50:25:25, 1.5 times by mass of dioxane was added to the total mass. To the obtained mixture, azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) were added as initiators in proportions of 1 mol% and 3 mol%, respectively, with respect to the total number of moles of all monomers. This was heated at 77 ° C. for about 5 hours. Thereafter, the reaction solution is purified by pouring it into a large amount of methanol / water mixed solvent (3: 1) and precipitating three times, and the weight average molecular weight is about 8.0 × 10 ^3. The coalescence was obtained in 60% yield. This copolymer has a structural unit derived from each monomer of the following formula, and this was designated as resin A2.

合成例３：樹脂Ａ３の合成
式（Ａ）で表されるモノマー、式（Ｆ）で表されるモノマー、式（Ｂ）で表されるモノマー、式（Ｃ）で表されるモノマー及び式（Ｄ）で表されるモノマーをモル比３２：７：８：４３：１０で仕込み、全モノマー量の１．５重量倍のジオキサンを加えて溶液とした。そこに開始剤としてアゾビスイソブチロニトリルとアゾビス（２，４−ジメチルバレロニトリル）を全モノマー量に対してそれぞれ１ｍｏｌ％、３ｍｏｌ％添加し、７３℃で約５時間加熱した。その後、反応液を、大量のメタノールと水の混合溶媒に注いで沈殿させる操作を３回行って精製し、重量平均分子量が８．９×１０^３の共重合体を収率７８％で得た。この共重合体は、次式の各モノマーから導かれる構造単位を有するものであり、これを樹脂Ａ３とした。

Synthesis Example 3: Synthesis of Resin A3 Monomer represented by Formula (A), Monomer represented by Formula (F), Monomer represented by Formula (B), Monomer represented by Formula (C) and Formula ( The monomer represented by D) was charged at a molar ratio of 32: 7: 8: 43: 10, and 1.5 weight times dioxane of the total monomer amount was added to prepare a solution. 1 mol% and 3 mol% of azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile) were added as initiators to the total monomer amount, respectively, and heated at 73 ° C. for about 5 hours. Thereafter, the reaction solution was purified by pouring it into a mixed solvent of a large amount of methanol and water three times to obtain a copolymer having a weight average molecular weight of 8.9 × 10 ^{3 in} a yield of 78%. . This copolymer has a structural unit derived from each monomer of the following formula, and this was designated as resin A3.

  As shown in Table 1, a resist composition was prepared by filtering a mixture obtained by mixing and dissolving the following components through a fluororesin filter having a pore size of 0.2 μm.

<Resin>
Resins A1 to A3
<Acid generator>
Acid generators B1 to B6: salt represented by formula (B1) to hydrochloric acid generator X1 represented by formula (B6)

<Basic compound: Quencher>
Quencher C1: 2,6-diisopropylaniline <solvent>
Propylene glycol monomethyl ether acetate 265 parts 2-heptanone 20.0 parts Propylene glycol monomethyl ether 20.0 parts γ-butyrolactone 3.5 parts

An organic antireflective coating composition [ARC-29; manufactured by Nissan Chemical Co., Ltd.] was applied onto a 12-inch silicon wafer and baked at 205 ° C. for 60 seconds to obtain a thickness of 780 mm. An organic antireflection film was formed. Next, the above resist composition was spin-coated on the organic antireflection film so that the film thickness after drying was 85 nm.
After applying the resist composition, the obtained silicon wafer was pre-baked (PB) for 60 seconds on a direct hot plate at the temperature described in the “PB” column of Table 1. Using the ArF excimer stepper for immersion exposure [XT: 1900 Gi; manufactured by ASML, NA = 1.35, 3/4 Annular XY deflection] on the wafer on which the resist composition film is formed in this manner, the exposure amount is stepwise. The line and space pattern was subjected to immersion exposure.
After the exposure, post exposure bake (PEB) is performed on the hot plate at a temperature described in the “PEB” column of Table 1 for 60 seconds, and further with a 2.38 mass% tetramethylammonium hydroxide aqueous solution for 60 seconds. Paddle development was performed.
In each resist film, the exposure amount at which the 50 nm line and space pattern becomes an exposure amount of 1: 1 was defined as the effective sensitivity.

Resolution evaluation: In terms of effective sensitivity, a resist pattern was observed with a scanning electron microscope. A resolution of 45 nm was evaluated as ◯, a resolution was not resolved, and a pattern collapse was observed as x.

Line edge roughness evaluation (LER): The surface of the resist pattern after the lithography process is observed with a scanning electron microscope, and the contact width of the unevenness on the side wall of the resist pattern is 5 nm or less. did. The numerical value in the parenthesis represents the touch width (nm) of the unevenness on the side wall of the resist pattern.

  According to the salt of the present invention, a pattern having excellent resolution and line edge roughness can be obtained from a resist composition containing the salt.

Claims (7)

A salt represented by the formula (I).

[In the formula (I),
Q ¹ and Q ² each independently represent a fluorine atom or a C _1-6 perfluoroalkyl group.
L ¹ represents a C _1-17 alkylene group, and —CH ₂ — contained in the alkylene group may be replaced by —O— or —CO—.
R ¹ represents a C _1-12 hydrocarbon group.
Ring W ¹ represents a C _3-36 saturated hydrocarbon ring.
R ² represents a C _1-6 alkyl group or a C _1-6 alkoxy group.
s represents the integer of 0-2. When s is 2, two R ² may be the same or different.
R ³ represents a group represented by the formula (R ³ -1), a group represented by the formula (R ³ -2) or a group represented by the formula (R ³ -3).

[In Formula (R ³ -1), A ¹ represents a C _1-6 alkylene group.
R ⁴ represents a C _1-6 alkyl group. ]

[In formula (R ³ -2), R ⁵ , R ⁶ and R ⁷ each independently represents a C _1-6 alkyl group. ]

[In the formula (R ³ -3), R ^{5 ′} , R ^{6 ′} and R ^{7 ′} each independently represents a C _1-6 alkyl group. ]
t represents an integer of 1 to 3. When t is 2 or 3, the plurality of R ³ may be the same or different.
Z ⁺ represents an organic counter ion. ] L ¹ is * —CO—O— or * —CO—O—CH ₂ —CO—O— (* represents a bond to —C (Q ¹ ) (Q ² ) —). 1. The salt according to 1. The salt according to claim 1 or 2, wherein Z ⁺ is a triarylsulfonium cation.   The acid generator containing the salt in any one of Claims 1-3.   A resin comprising the acid generator according to claim 4 and a resin, wherein the resin has an acid labile group and is insoluble or hardly soluble in an alkaline aqueous solution, and is soluble in an alkaline aqueous solution by the action of an acid. A resist composition.   Furthermore, the resist composition of Claim 5 containing a basic compound. (1) The process of apply | coating the resist composition of Claim 5 or 6 on a board | substrate,
(2) The process of drying the composition after application | coating and forming a composition layer,
(3) a step of exposing the composition layer using an exposure machine;
(4) A step of heating the composition layer after exposure,
(5) a step of developing the heated composition layer using a developing device;
A method for producing a resist pattern including: